Girly girl, Hmm. You could get down to boots or another perfume shop and smell the following, see which you like. (if you like it, thats half the battle as you wont want her wearing something you dont like!)
Not necessarily recommending buying at Boots but good place to try them.
Sunkissed Glow by JLo Eau de Toilette 100ml
Ghost Sweetheart Eau de Toilette 30ml
Sarah Jessica Parker The Lovely Collection Endless Eau de Parfum 75ml
This one has a special offer at boots though, its a smaller bottle you can carry in your handbag, along with a refill. Marc Jacobs Daisy Refillable Purse Spray 20ml & Refill 15ml
The boots prices for all of these are between �23-28. But if you search on the internet you should be able to get the prices down.
Also, i wouldnt worry too much about EDT vs Parfum. it just means the EDT is lighter, which if it is a perfume she doesnt know, is not a bad thing. If you find one she likes, then next present can be the parfum or body lotions!